in County Clare, Ireland]]A dolmen (also known as cromlech, anta, Hünengrab, Hunebed, quoit, and portal dolmen) is a type of single-chamber megalithic tomb, usually consisting of three or more upright stones (megaliths) supporting a large flat horizontal capstone (table).Most date from the early Neolithic period (4000 BC to 3000 BC). Dolmens were usually covered with earth or smaller stones to form a barrow, though in many cases that covering has weathered away, leaving only the stone "skeleton" of the burial mound intact.
Etymology
"Dolmen" originates from the expression taol maen, which means "stone table" in Breton, and was first used archaeologically by Théophile Corret de la Tour d'Auvergne. The etymology of the German Hünenbett or Hünengrab and Dutch Hunebed (lit. Huns' bed) all evoke the image of giant building the structures. Of other Celtic languages, "cromlech" derives from Welsh and "quoit" is commonly used in Cornwall. Anta is the term used in Portugal, and dös in S
Source:
http://en.wikipedia.org/wiki/Dolmen